Several genetic loci determining quantitative variation in the enzymes beta-galactosidase and pancreatic amylase have been identified. Both enzymes have been purified, and monospecific antisera prepared. We propose to determine the effect of these mutations on the rate of enzyme synthesis, degradation, and hormonal induction. The chromosomal location of certain loci determining complex traits will be determined using Recombinant Inbred Lines. The genetic control of pancreatic amylase is being studied in congenic strains carrying alternative alleles at the amylase loci. The ability of lysosomes from mutant mice with defective lysosomal secretion to undergo in vitro fusion will be investigated. These studies will contribute to our understanding of the mechanisms of genetic regulation in mammals.